50 MeV Li3+ irradiation effects on the thermal expansion of Ca1-xSrxZr4P6O24

The influence of 50 MeV Li3+ ion irradiation on the thermal expansion of the low thermal expansion ceramic Ca1-xSrxZr4P6O24 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) belonging to the sodium zirconium phosphate (NZP) family of ceramics was studied in the temperature range 300-1100 K. The observed changes in XRD, microstructure and thermal expansion are reported. These changes are strongly dependent upon the strontium substitution at calcium sites in the basic structure, The XRD and scanning electron microscope (SEM) studies indicate that the ion irradiation causes amorphization, especially at the grain boundaries. The thermal expansion hysteresis reduces due to Sr substitution and is further reduced upon irradiation. It is suggested that the amorphization due to irradiation helped release of thermal stress and thereby lead to the reduction in the hysteresis in thermal expansion. The composition with x = 0.50 having low coefficient of thermal expansion (CTE), low hysteresis and the least thermal expansion anisotropy is least affected by the Li3+ irradiation and hence may qualify as the radiation resistant material. (C) 2002 Elsevier Science B.V. All rights reserved.